Schools, Science and Education

Sweller’s Cognitive Load Theory (CLT) may be the single most important thing for teachers to know, but it was not necessarily designed with teachers in mind. The product of lab-based randomised controlled trials, it is a theory from the specific academic discipline Cognitive Science. In recent years teachers have found it incredibly useful and many blogs and books have been written trying to explain it and how it can be utilised in front-line education.

In my experience, most will use Willingham’s graphic below in order to explain CLT:

A very general reference to the working memory being limited will be made, and a discussion of how if it is “overloaded” learning cannot occur. To me, this is too general to be enormously useful (1). Often, blogs and articles can be more helpful by identifying specific aspects of CLT like dual coding or chunking, and though this is incredibly important, it doesn’t represent the full picture: it doesn’t give me enough to think about the load whatever the particular scenario.

In the technical literature, CLT is normally described by reference to extraneous, intrinsic and germane load. I have personally always found these terms to be a little cumbersome, and despite there being readable explanations out there like this, I’ve never particularly found the idea helpful.

A different presentation can be found in Frederick Reif’s book Applying Cognitive Science to Education. A physics educator by training, Reif has a very careful and analytic approach to tackling the issues that is often simplified into more readily understood presentations. His version of CLT reads as follows:

The science teacher in me really likes this. When presenting students with a formula like this, we would explain that increasing “task demand” increases load, whereas increasing “available resources” decreases load. Load, resources and demand are variables: they are things that can change, or be kept the same. This is important because there are some things that might be out of our control, and if that is the case we must manipulate the other variables to compensate. For example, the task demand of a GCSE paper is out of our hands, so we must therefore increase the resources available to the student to lower the overall load.

Before we look at the different parts of the equation, it is important to note that Reif is very clear that we should not be aiming to just lower the load as much as possible. He argues that if we do this the learning will take an incredibly long time as we make tasks smaller and smaller but also, importantly, that it will become exceedingly boring and demotivating for the student.

Let’s drill down into available resources first. This part of the equation can be thought of as the sum of two new variables:

Internal resources refers to the knowledge bank which a student has to bring to a particular task. This is where chunking and prior knowledge comes in: the more knowledge a student has of a particular domain, the easier it is for them to solve tasks relating to that domain. As teachers, we control this variable as much as possible through long-term memory strategies like retrieval practice, spacing practice and interleaving practice (2).

External resources refer to the physical objects from the environment that the student can use. In maths, this might be as simple as the use of a calculator or a piece of paper and a pen to do working on. In other subjects (including science) you might use a vocabulary wall which you can see demonstrated by Jo Facer here. In science specifically even the section on the periodic table where labels are shown pointing to “atomic number” and “mass number” will increase the external resources available to a student when they are working out the number of neutrons in a given atom. A step-by-step guide or list of rules for following a procedures would also probably count as external resources.

It might be interesting to consider attentional effects here as well. Though Reif does not discuss this, a quiet and orderly classroom is conducive to thinking and learning. If the classroom is noisy and distracted, then perhaps the external resources become lowered.

Task demand refers to the actual task which the student is completing. Reif discusses two ways of breaking down a task to lower its demand:

Quantity is the simplest to explain, as it just refers to the number of things in a particular task. So instead of asking students to derive and balance a particular symbol equation equation from a piece of text, you can break that down into 1) write a word equation 2) derive the formulae for each substance 3) construct a symbol equation 4) balance the symbol equation. In English for example, you might want students to be able to answer the question “How is Slim presented in this extract?” and break it down into 1) find a quotation that shows Slim being presented as empathetic, 2) analyse the methods the writer has used to show that he is empathetic, and so on for other characteristics (3).

I didn’t fully follow his explanation of quality, so in the interests of keeping this article simple, I’m not going to go into it. I don’t think as Reif describes it there are many useful applications in class (4).

Overall, we are therefore left with the below:

In my opinion, this mental model is a helpful framework for teachers to use when planning for learning. We can’t always control each of the variables, but by understanding that they relate to each other we can manipulate the ones we can control to result in an optimum load.

(1) I am of course aware that Willingham goes into more detail in his book and I highly recommend teachers read it. I am referring more to the “secondary” literature that has sprung up around it.

(2) For more reading on any of the concepts referred to throughout this blog, click here.

(3) Many thanks to Rebecca Foster for helping me out with this though I have probably misunderstood. English is not exactly my strong point…she has a brilliant blog about tackling complex tasks like writing an essay here.

(4) My understanding of quality runs as follows: it posits that there is some product you want to see from your students, which we will call P. If students are solving physics problems, P would be “interpret a text, extract the correct quantities, use and manipulate the correct formula, calculate answer, provide units.” A quantity model would just break all that up into smaller parts, so a bunch of questions on establishing correct quantities from texts, a bunch on manipulating formulae etc. A quality model says let us take an approximation of P, perhaps “describe how the quantities in a given text relate to each other.” This is a different type of task and gives students a series of approximations of P.

Adam

41 thoughts on “Simplifying Cognitive Load Theory”

Perhaps quality may be classified as the variable to express the relevance of the task to understanding the topic and the subject curriculum. Thanks for another humbling post; don’t know how bloggers such as yourself find the time to publish useful, thoughtful content…

The interpretation of the variable ‘quality’ could be that, using the analogy of balancing a chemical equation, quality represents the teacher asking: does the student need to know in this cognitive load equation model, the reactants and products? Or oxidation states to balance the equation correctly? If the former, the teacher could re-evaluate the task to lower the cognitive load (for now) to restricting the task to correct names of reactants and products, i.e. write a correct word equation.

Another separate task would then be prepared to practice appropriate chemical equation balancing

This looks useful, and I will be interested to see if teachers find it helpful. I have only one comment, and it is a clarification more than an objection. I think it is important to make clear that “external resources” also includes things like the notes that students make on pieces of paper to help them think through the problems that they are working and not just things they are given. The idea that thinking is not just inside the head is what David Perkins many years ago called “person plus” and is often described by psychologists as “distributed cognition”.

Thank you for the comment – I also hope that people find it useful and look forward to seeing what people come up with. I also completely agree that available resources includes jotting paper, can be extremely important when planning longer answers as well as in complex calculations…in my experience of science perhaps in 6 markers at GCSE or long syntheses or analytic routes if students do not use spare paper as a kind of extension of their working memory they inevitably make mistakes!

Yes, this clarification reminded of reading some recent articles about the impact of different styles of note-taking (e.g. https://pubs.rsc.org/en/content/articlehtml/2019/rp/c8rp00214b?page=search ‘Too much information’). Admittedly this article is beyond school level, but the principle is the same and should prompt the teacher to make a more detailed review of students’ notes. This was recently experienced when reviewing students’ notes about thermodynamics and a realising a notable quantity of students failing (despite specific instruction!) to draw correct energy profile diagrams. It became a starter activity of a subsequent lesson.

Very difficult question. I think to an extent this is the role of the expert teacher responding to their class, making sure the work is *always* at the point where students’ load is such that it is isn’t too low as to prevent actual thought, but isn’t too high as to demotivate or embed mistakes

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